Telescopic power cylinder and method of making same



C. E. MARGALA Filed March 6, 196].

FIG. 2

CHARLES E. MARGALA July 31, 1962 TELESCOPIC POWER CYLINDER AND METHOD OFMAKING SAME FIG. I

United States Patent Ofiice dfi ihfi ih Patented July 31, 1%62 3,946,948TELECOPIC PGWER EYLINDER AND METHGD F MAKENG AME Charles E. Margaia,Z610 Hubbard Road, Youngstown, fihio Filed Mar. 6, 1951, Ser. No. 93,7232 Claims. (Cl. 121-45) This invention relates to telescopic powercylinders and more particularly to improved yet simplified features ofdesign for such cylinders and to improved yet simplified methods formanufacturing such cylinders. Telescopic cylinders are commonly employedfor moving heavy loads through long strokes as, for example, in raisingthe forward ends of large heavily laden bodies of material-hauling roadvehicles to dump the loads therefrom. In such applications the reactiveforces are very large-requiring powerful moving forces and greatcolumnar strength in the cylinder when extended. To keep the physicalsize and weight of the cylinders within practical limits it is desirableto reduce the side wall thicknesses of the tubing normally employed byemploying high quality drawn tubing and to minimize the diameters of thetube sections by employing very high hydraulic pressures 5000 psi. ormore. Heretofore, these desirable objectives were obtained only at theexpense of decreased strength and reliability and of intricatemachining, making such cylinders extremely costly.

It is accordingly the primary object of this invention to improve thedesign and construction of telescopic cylinders whereby the same mayhave great strength yet be light in weight, small in size, capable ofwithstanding very high hydraulic pressures and be capable of beingeconomically produced. An ancillary object of the invention,

and one flowing inherently from the general principles of the invention,is the maximum utilization of the great dependable strength ofhigh-quality cold drawn seamless tubing through the substantiallyelimination of machiningon the tubing lengths. Machining normally hasthe eflect of weakening the sect ons.

The above objects are accomplished by the present invention primarily byutilizing, as the principal structural elements of the cylinder, aplurality of lengths of cold drawn seamless tubing each being of uniformcross section throughout its length but being of graduated diameters toallow for telescoping. Welded to the inner and outer cylindricalsurfaces of these lengths are stop and stabilizing rings which limit therelative outwar movement of the tubing lengths or sections and whichhold the assembled sections in axial alignment for maximum columnarstrength. The rings are fairly accurately fitted and since weld beads ofsubstantial length may be applied the rings are tightly held even withshallow penetration of weld heat. Thus, the principal structuralcomponents-the tubing lengths-are not weakened. Suitable hearing orlow-friction metal to provide the sliding contact between the sectionsmay be applied directly to certain of the Welded rings or by means ofadditional risgs as will appear below.

For a better understanding of the advantages provided by my inventionreference is now made to a specific preferred embodiment of theinvention as described in the following specification and shown in theaccompanying drawing wherein:

FIGURE 1 is a longitudinal section of a telescopic cylinder constructedin accordance with the principles of the invention; and

FIGURE 2 is a fragmentary sectional detail of the assembly of FIGURE 1.

While in the drawing I have shown a cylinder comprised of only threetelescoping tube lengths or sections it should be obvious, as thedescription proceeds, that the principles of the invention are equallyapplicable to cylinders having a much larger number of sections and to acylinder having but two sections. Reference numeral 10 designates alength of tubing which is of largest diameter in the assembly shown andwhich is preferably of high-quality cold drawn seamless tubing.Reference numeral 11 designates a length of the smallest diameteredtubing which is closed off at its upper end by a cap 12 preferablywelded thereto. An intermediate tubing length is shown at 13.

In the construction of the assembly of FlGURE l, a steel ring is weldedto the inner wall of each of the solid lengths it and 13, such ring inthe length it being designated by the reference numeral 14 while suchring in the length 13 is designated by the numeral 15. As shown, therings 14- and 15 are adjacent to but are spaced inwardly from the upperends of the lengths 1t? and 13, respectively, and these rings performtwo functions. First, they serve as stop rings to cooperate with otherstop rings to be hereinafter described to limit outward movement of thelength 13 with respect to the base length 10 and outward movement of thelength 11 with respect to the length 13. Secondly, the rings 14- and 15serve as inner retainers for packings which are placed between lengths10 and 13 and between lengths i3 and ill to seal the oil in theassembly.

In actual practice the rings 14 and 15 may be obtained simply by cuttingoif short lengths of other seamless tubing as will be understood but,however obtained, it is desirable that the outer cylindrical surface ofthe rings have a snug sliding fit with the inner cylindrical surface ofthe tubing lengths lb and 13 at time of assembly so that the rings maybe rigidly and strongly secured within the tubing lengths with a minimumapplication of welding heat. it should be appreciated that thecircumferential lengths of the interengagements of the rings with thetubing lengths are quite substantial so that very long welding beads maybe drawn and even though the filets are quite small and the depth ofpenetration of the welding heat is rather shallow, the strength of theattachment will be quite substantial-particularly in an axial directiontending to drive the rings out of the tubing lengths. Of course, arcwelding is preferably used and the sharp corners formed between theaxial ends of the rings and the adjacent side walls of the tubinglengths provide excellent confining surfaces for the formation of thewelding beads.

The tubing lengths 1d and 13 are formed at their upper end portions withshallow external threads to receive the internally threaded bezel rings16 and 17, respectively. Since these threads may be quite fine andshallow they do not appreciably Weaken the top end portions of the tubesit and 12 and, further, it should be noted that these threads arelocated where great strength in the tubing lengths is not required.

Welded to the outer walls of tubes 11 and 13 adjacent to but spacedupwardly from the bottom ends thereof are the stop rings 18 and 19,respectively, and, again, these rings are preferably solid steel, aresized to have a fairly close fit with the outer cylindrical surfaces ofthe tubing lengths, and are welded to the tubing lengths in the mannerrecited for rings 14 and 15. The function of rings 18 and 19 is toengage the rings 15 and 14-, respectively, and thereby limit the outwardmovement of tube 11 with respect to tube 13 and the outward movement oftube 13 with respect to tube It A stabilizing ring 20 is welded to theouter surface of tube 11 at the bottom end thereof below the ring 13,and a similar ring 21 is similarly welded to the bottom end of tube 13.After the rings 20 and 21 are welded onto the tubes 11 and 13 the outerperipheries of these rings are metalized with brass or some othersuitable low-friction metal to form a substantial adhered layer of suchmetal as shown at 22 in FIGURE 2. After metalizing the rings 2(3 and 21may be turned or ground to provide anaccurate sliding fit with theinternal suitaces of the tubes 13 andlll, respectively.

It should be understood that with the parts described above being firstassembled in the manner indicated the tubing length 11 may be insertedinto the tubing length 13 from the bottom end thereof While the tubinglength 13 may be inserted into the tubing length from the bottom endthereof. At this final assembly "a ring 23 of suitable bearing metal isplaced immediately above the ring in the tubing length 13, and in actualpractice the tube 11. Thus the tube 11 is accurately guided for axialmovement in the tube 13'by the bearings provided by the ring 23 and bythe adhered layer on the outer periphery of ring 21 These bearingsurfaces mayeliminate all steeLto-steel rubbing contact and therebyprevent galling of the parts in actual use. 'It should also be notedthat this construction enables the internal diameter of ring 15 to beinitially made slightly oversize while the external diameter of ring 18undersized so that any distortion of the ring as may take place duringwelding will have not adverse effect in the final product. A ring 24having the same function and relative specifications as the ring 23 ispositioned in the tube 10 above the ring 14.

At final assembly the space within tube .10 above the ring 24 is filledwith a suitable packing 25 which may be of the chevron type, forexample, and engaging the top of this packing is a shouldered ring 26made of brass or other anti-friction metal and carefully machined tohave the snug sliding fit with the cylindrical outer surface of thetubing length 13. -As shown, the shoulder on ring 26 is engaged by theinwardly directed flange of the bezel ring 16 so that as the latter isscrewed down onto the tubing length 10 the packing 25 will be suitablycompressed to accomplish its sealing function. it should be noted,additionally, that the ring 26 is effectively held against lateralmovement by the ring 16 and since these parts are, in actual practice,made rather heavy the ring 26 will aid materially in lending lateralstability to the tubing'length 13 with respect to the tubing length 10and thereby increase the columnar strength of the assembly.

Positioned above the ring 23 in tubing lengthllris a packing 27 similarto packing 25 and, a shouldered antifriction packing ring 28 ispositioned the bezel ring 17 to compress packing 27 and to assist inguiding the axial movement of tubing length 11. 7

One or more apertures may be made in the Wall of the tubing length 10 topermit the ingress andegress of hydraulic fluid pressure which may beconducted, for example, by the conduits 29 and 30 shown'in the drawasdescribed above, are nested together in operative positions the lowerend of the tubing length 10 may be sealed oif by welding on a base plate3 1. There is thus provided acomplete'closed telescoping cylinderassembly which will expand or extend when hydraulic fluid pressure isfurnished the conduits 29*andf3il "and which will collapse to a minimumoverall length or height when a suitable closing force is applied andthe hydraulic fluid allowed to bleed off through the conduits 29 and 30.

pin, not shown, which passes through a bore 36 formed in the cap 12theaxis of 'bore '36 being parallel with the shaft 32. i

It should now be apparent that I have provided an improved telescopiccylinder assembly and an improved method of constructing the same whichaccomplishes the objects initially set out. Maximum use is made ofsimple lengths of commercial cold drawn seamless tubing which underpresent standards is highly accurate as to size and concentricity and isof great strength. The individual cut lengths are readily prepared forassembly'simply by providing the threads or equivalent expedient toreceive the pacldng rings and by welding on the desired'rings asdescribed above. Soprepared, the individual lengths are readilyassembled into the telescopic unit afiter which the assembly is closedby welding on the base plate 31.

The manufacture of the assembly is accomplished with a minimum of laborand because practically no ma chining is done on the Walls of theseamless tube lengths the great strength of these principal componentsis unimpeded. As a result theassembly has maximum mechanical (columnar)and pressure strength for the size and weight of materials employed.

diameter having welded to its outer wall and adjacent its inner end asolid metal ring, saidsecond mentioned rings being adapted upon outwardsliding movement of said lengths to contact said first mentioned ringsand thereby limit the outward movement of all of said lengths except forthe one of largest diameter, packing'placed in the outer end portion ofthe tube lengths to which said first mentioned rings are respectivelywelded and retainedby said rings, means carried by said outer endportions and encircling the outer walls of the next smaller diameter 7tube lengths to engage and compress said packings, solid metalstabilizing rings, devoid of grooves, welded to the outer wall of eachof said tube lengths except the one of largest diameter and positionedat the inner ends of said lengths in spaced relation to the above secondmentioned rings which are also welded onto said lengths, the outerperipheral surfaces of said stabilizing rings being faced with anadhering layer of low-friction metal of a thickness to provide anaccurate sliding fit with the inner walls of the surrounding tubes, acap for the outer free end of the tube length of smallest diameter, anda cap welded onto the free end of the tube length of largest diametering. After all of the tubing lengths, with rings attached pansive forcebetween said caps. V

2. Apparatus according to claim 1 further including a ring oflow-friction metal in contact with each of said packings and adapted toslidably engage the outer walls of the tube lengths received in saidpackings, the arrangement being such that thetelescoping of said tubelengths is guided primarily by said rings of low-friction metal and saidlayers of low-friction metal and while the first and second mentionedrings may be free of sliding contact with the tube lengths.

References Cited in the file of this patent UNITED STATES PATENTS WoodAug. 1, 1950

